pulse on fingers

[amocar]

I am an engineering student and currently doing my thesis. It is related with pulse rate. I want to know why the pulse oximeter is designed for fingers even if the pulse sites do not include our fingers? Anyone who can share their idea? or if you have any info regarding pulse on our fingers will do.  tnx in advance. waiting with anticipation. :-)

[amocar]

Hi, thank you Dr. Sharma. According to my readings, our pulse rate is lower when we are sleeping than we are awake. Is there a mathematical relationship or specific calculation of our pulse rate when asleep and when not?

[Dr Sharma]

Hi there. Pulse oximetry is a monitoring technique in the operation theatres and intensive care units used to check the saturation pressure of oxygen at the given atmospheric oxygen levels.
It uses a light emitter with red and infrared LEDs that shines through a reasonably translucent site  with good blood flow. Typical sites are finger, toe, pinna or the ear lobe for adults and infant sites are the foot and palm of hand and big toe or thumb. Opposite the emitter is a photodetector that receives the light that passes through the measuring site.
So it does not check the pulse but checks the percentage of oxyhemoglobin visavis deoxygenated hemoglobin. Pulse rate is an indirect derivation.
The oxygen saturation percentage is calculated by the way red and infrared lights are absorbed and transmitted by the oxy and deoxy hemoglobins.
Take care.